Packaged microelectronic devices with pressure release elements and methods for manufacturing and using such packaged microelectronic devices

ABSTRACT

Packaged microelectronic devices, interconnecting units for packaged microelectronic devices, and methods and apparatuses for packaging microelectronic devices with pressure release elements. In one aspect of the invention, a packaged microelectronic device includes a microelectronic die, an interconnecting unit coupled to the die, and a protective casing over the die. The interconnecting unit can have a substrate with a first side and a second side to which the die is attached, a plurality of contact elements operatively coupled to corresponding bond-pads on the die, and a plurality of ball-pads on the first side of the substrate electrically coupled to the contact elements. The protective casing can have at least a first cover encapsulating the die on the first side of the substrate. The packaged microelectronic device can also include a pressure relief element through at least a portion of the first cover and/or the substrate. The pressure relief element can have an opening to an external environment and a passageway to an internal location within the packaged microelectronic device. In operation, the pressure relief element releases gases or other forms of moisture entrapped by the casing and/or the substrate during high temperature processing of the packaged microelectronic device.

TECHNICAL FIELD

[0001] The present invention relates to packaging microelectronicdevices having a microelectronic die including an integrated circuit.More particularly, several aspects of the invention are related toreleasing pressure within packaged microelectronic devices during hightemperature processes, such as reflow processing and burn-in testing.

BACKGROUND

[0002] Microelectronic devices, such as memory devices andmicroprocessors, typically include a microelectronic die encased in aprotective covering. The die can include memory cells, processorcircuits, interconnecting circuitry and/or other functional features.The die also typically includes an array of very small bond-padselectrically coupled to the functional features. When the die ispackaged, the bond-pads are coupled to leads, solder ball-pads or othertypes of terminals for operatively coupling the microelectronic dies tobuses, circuits and/or other microelectronic devices.

[0003] Several different techniques have been developed for packagingmicroelectronic dies. The dies, for example, can be incorporated intoindividual packages, mounted with other components in hybrid or multiplechip modules, or connected directly to a printed circuit board or othertypes of substrates. When a die is incorporated into an individualpackage, the bond-pads on the die are typically coupled to a lead frame,and the die is covered or otherwise sealed from the environment. Whenthe die is attached directly to a printed circuit board or another typeof substrate, the bond-pads on the die are typically coupled tocorresponding contact elements on the substrate using wire-bond lines,ball grid arrays and other techniques. The dies that are mounteddirectly to the substrates are generally Chip Scale Package devices(CSP) or Flip Chip Bare Die devices (Flip-Chip).

[0004] CSP and Flip-Chip devices generally have one or more protectivecasings that encapsulate the dies and any exposed contact elements,bond-pads or wire-bond lines. The protective casings should shield thedie and the other components on the substrate from environmental factors(e.g., moisture), electrical interference, and mechanical shocks. Theprotective casings are accordingly robust elements that protect thesensitive components of a microelectronic device. The protective casingsare generally composed of plastics, ceramics, or thermosettingmaterials.

[0005] One conventional technique for fabricating the protective casingsinvolves placing the die in a cavity of a mold, and then injecting athermosetting material into the cavity. The thermosetting material flowsover the die on one side of the substrate until it fills the cavity, andthen the thermosetting material is cured so that it hardens into asuitable protective casing for protecting the die. According toconventional practices, the protective casing should not have any voidsover the die because contaminants from the molding process orenvironmental factors outside of the mold could damage the die. Thethermosetting material, moreover, should not cover a ball-pad array onthe substrate or damage any electrical connections between the die andthe substrate. Therefore, according to conventional practices, thethermosetting material should be molded in a manner that avoids (a)producing voids in the protective casing, (b) covering certain portionsof the substrate with the thermosetting material, and (c) displacing orotherwise damaging any wire-bond lines or solder joints between the dieand the substrate.

[0006] One drawback of packaging microelectronic devices is that duringhigh-temperature processing cracks or voids can form in the protectivecasing, or the protective casing can delaminate from the substrate. Suchcracking or delamination, for example, may occur during a solder reflowprocedure in which the packaged microelectronic devices are quicklyheated to reflow solder balls and/or or solder paste pads. This problemis particularly noticeable in procedures that quickly heat the packageddevices to an elevated temperature. When the casing of a packagedmicroelectronic device cracks or delaminates from the substrate, thedevice is often rejected because such cracks or voids can expose verydelicate components (e.g., bond-pads or wire-bond lines) to externalenvironmental factors. It will be appreciated that such cracking of thecasing results in extremely expensive losses because it occurs at theend of the fabrication process after a significant amount of money hasbeen expended to manufacture each packaged microelectronic device.Therefore, it would be desirable to develop an apparatus and method forreducing or completely preventing the casing from cracking ordelaminating from the substrate during high temperature processing.

SUMMARY

[0007] The present invention is directed toward packaged microelectronicdevices and methods for making and using such packaged microelectronicdevices. In one aspect of the invention, a packaged microelectronicdevice includes a microelectronic die, an interconnecting unit coupledto the die, and a protective casing over the die. The microelectronicdie, for example, may have an integrated circuit and a bond-pad arrayhaving a plurality of bond-pads operatively coupled to the integratedcircuit. The interconnecting unit has a substrate with a first side anda second side to which the die is attached, a plurality of contactelements operatively coupled to corresponding bond-pads on the die, anda plurality of ball-pads on the first side of the substrate. Theinterconnecting unit can also include a plurality of conductive elementsextending from selected contact elements to corresponding ball-pads toelectrically couple the contact elements to the ball-pads. Theprotective casing can have at least a first cover encapsulating the dieon the first side of the substrate.

[0008] The packaged microelectronic device can also include a pressurerelief element through at least a portion of the first cover and/or thesubstrate. The pressure relief element can have an opening to anexternal environment and a passageway to an internal location orinterior point within the packaged microelectronic device. The pressurerelief element, for example, can be a hole or opening through thesubstrate to an adhesive strip on the bottom side of the die. In anotherembodiment, the pressure relief element is a hole through the firstcover to either the substrate or the microelectronic die. In stillanother embodiment, the pressure relief element is a depression thatextends only part way through the cover or the substrate such that thepassageway forms a thin section of the first cover or the substrate. Inoperation, the pressure relief element releases gases or other forms ofmoisture entrapped by the casing and/or the substrate during hightemperature processing of the packaged microelectronic device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a top cut-away isometric view illustrating a portion ofa microelectronic device in accordance with an embodiment of theinvention.

[0010]FIG. 2A is a top isometric view of the microelectronic device ofFIG. 1.

[0011]FIG. 2B is a front cross-sectional view of the microelectronicdevice of FIG. 2A.

[0012]FIG. 3 is a front cross-sectional view of a microelectronic devicein accordance with another embodiment of the invention.

[0013]FIG. 4A is a bottom isometric view and FIG. 4B is a frontcross-sectional view of a microelectronic device in accordance withanother embodiment of the invention.

[0014]FIGS. 5A and 5B are front cross-sectional views of amicroelectronic device in accordance with another embodiment of theinvention.

[0015]FIGS. 6A and 6B are front cross-sectional views of amicroelectronic device in accordance with still another embodiment ofthe invention.

[0016]FIG. 7 is a side cross-sectional view of a microelectronic deviceand a mold assembly used to form a protective casing with pressurerelief elements in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0017] The following disclosure is directed toward packagedmicroelectronic devices, interconnecting units for packagedmicroelectronic devices, and methods for manufacturing and usingpackaged microelectronic devices. Several embodiments of the inventionare described with reference to memory devices, but the methods andapparatuses are also applicable to microprocessors and other types ofdevices. One skilled in the art will accordingly understand that thepresent invention may have additional embodiments, or that the inventionmay be practiced without several of the details described below.

[0018]FIG. 1 is a top cut-away isometric view of a microelectronicdevice 10 in accordance with one embodiment of the invention. Themicroelectronic device 10 can include a substrate 20 and amicroelectronic die 40 attached to the substrate 20 by an adhesive strip60. The following description is directed toward encapsulating amicroelectronic die on a flexible substrate, but it is expected thatseveral embodiments of the methods and apparatuses in accordance withthe present invention may be practiced to encapsulate a large variety ofelectrical and/or non-electrical articles. Therefore, the followingdescription with respect to encapsulating the microelectronic die 20shown in FIGS. 1-7B is for purpose of illustration only, and it is notintended to limit the scope of the invention.

[0019] The embodiment of the substrate 20 shown in FIG. 1 can have afirst end 21, a second end 22 opposite the first end 21, a first surface23, and a second surface 24 opposite the first surface 23. The substrate20 can also include an elongated slot 25 between the first and secondsurfaces 23 and 24 that extends lengthwise along a medial portion of thesubstrate 20. Additionally, an aperture 26 through the substrate 20 canbe located at a secondary gate location generally proximate to thesecond end 22 of the substrate 20. The substrate 20 is one component ofan interconnecting unit that provides an array of ball-pads for couplingvery small bond-pads on the microelectronic die 40 to voltage sources,signal sources, and/or other input/output sources. In the embodimentshown in FIG. 1, the substrate 20 includes an array of ball-pads 27, anarray of contact elements 28 proximate to the slot 25, and a trace 29 oranother type of conductive line between each ball-pad 27 and acorresponding contact element 28. The substrate 20 can be a flexiblematerial or a substantially rigid material, and the traces 29 can beconductive lines that are printed on the substrate in a manner similarto printed circuit boards.

[0020] The embodiment of the microelectronic die 40 shown in FIG. 1includes a front side 41, a plurality of bond-pads 42 on the front side41, and an integrated circuit 44 (shown schematically). The front side41 of the die 40 is attached to the second surface 24 of the substrate20 by an adhesive strip 60. The bond-pads 42 are coupled to theintegrated circuit 44, and the bond-pads 42 are also arranged in anarray along the front side 41 of the microelectronic die 40 so that thebond-pads 42 are aligned with or otherwise accessible through the slot25 in the substrate 20. A plurality of wire-bond lines 50 or other typesof connectors couple the bond-pads 42 on the die 40 to correspondingcontact elements 28 on the substrate 20. As such, the substrate 20distributes the very small bond-pads 42 to the larger array of ball-pads27. The die 40 projects away from the second surface 24 of the substrate20 such that a backside 45 of the die 40 is spaced apart from the secondsurface 24 of the substrate 20.

[0021] The microelectronic device 10 can further include a protectivecasing having a first cover 70 a over the die 40 and a second cover 70 bover the slot 25. The first and second covers 70 a and 70 b can beformed from a thermosetting material, ceramics, or other suitablematerials. The first and second protective covers 70 a and 70 b can bemolded as explained in U.S. patent application No. 09/255,554, which isherein incorporated by reference.

[0022] The embodiment of the microelectronic device 10 shown in FIG. 1also includes a plurality of pressure relief elements 80 that areconfigured to release a gas entrapped in the microelectronic device 10.The substrate 20 and/or the adhesive strip 60 can absorb moisture, andthe first and second covers 70 a and 70 b can entrap this moisture inthe area around the die 40. When the microelectronic device 10 isquickly heated in a solder reflow process or another high-temperatureprocedure, the entrapped moisture expands and creates a pressuregradient in the microelectronic device 10. The pressure relief elements80 provide a path through which the expanding gas can escape withoutcracking the covers 70 a or 70 b, delamninating the substrate 20 and/orthe covers 70 a or 70 b, or otherwise damaging the microelectronicdevice 10.

[0023]FIG. 2A is a top isometric view and FIG. 2B is a frontcross-sectional view that illustrate various embodiments of the pressurerelief elements 80 in further detail. Referring to FIG. 2A, the pressurerelief elements 80 can be a series of passageways completely through thesubstrate 20 at an area outside of the ball-pads 27. The pressure reliefelements 80 can be of elongated channels (shown on one side of the cover70 b), or the pressure relief elements 80 can be holes (shown on theother side of the second cover 70 b). The pressure relief elements 80can also be shorter elongated channels or slots that fit between theball-pads 27 and the traces 29 (shown in broken lines). In a typicalapplication, the pressure relief elements 80 will be either elongatedchannels on both sides of the second cover 70 b, or a series of holes onboth sides of the second cover 70 b (as shown in FIG. 1). Referring toFIG. 2B, the pressure relief elements 80 include a passageway 82 havinga first end defined by an opening 84 at an external location and asecond end at an interior point 86 of the microelectronic device 10. Inthe particular embodiment shown in FIG. 2B, the opening 84 is at thefirst surface 23 of the substrate 20 and the interior point 86 is at thesecond surface 24 of the substrate 20.

[0024] The pressure relief elements 80 of the embodiment shown in FIG.2B are also positioned over the adhesive strip 60 to expose a portion ofthe adhesive 60 to the external environment. The location of thepressure relief elements 80 is generally selected to provide apassageway to internal locations within the substrate where moisture islikely to be entrapped. Thus, as explained in more detail below, thepressure relief elements 80 can be configured to allow moisture toescape from the substrate 20, the adhesive 60, the covers 70 a and 70 b,and/or any combination of these components.

[0025] The pressure relief elements 80 shown in FIGS. 1-2B can be formedby etching or laser cutting the substrate 20 before attaching theadhesive 60 to the second surface 24 of the substrate 20. The pressurerelief elements 80, for example, can be etched by masking the substrate20 with a photo resist and etching through the substrate 20 with asuitable etchant. Similarly, a laser can cut through the substrate 20using techniques that are known in the art. The pressure relief elements80 can also be formed by mechanically drilling (e.g., gang drilling),punching, stamping, or molding the holes or slots in the substrate 20.

[0026] The microelectronic device 10 is particularly well suited for usein high temperature post-encapsulation processes, such as solder reflowprocessing and burn-in testing. When the microelectronic device 10 issubject to a process that rapidly increases the temperature, theexpansion of the moisture entrapped in the substrate 20, the adhesive60, and/or the first and second covers 70 a and 70 b generates apressure gradient in the internal region of the microelectronic device10. The adhesive tape 60, for example, is particularly subject toabsorbing moisture, and thus a pressure gradient typically forms in theregion of the adhesive 60 during high temperature processing. Thepressure relief elements 80 allow the moisture in the tape 60 and theother components of the device 10 to diffuse out of the device 10 beforelarge pressure gradients are created in the substrate 20 or the firstand second covers 70 a and 70 b. The pressure relief elements 80 areaccordingly expected to inhibit or completely prevent cracking ordelaminating of the covers 70 a and 70 b during high temperatureprocessing.

[0027]FIG. 3 is a front cross-sectional view of a microelectronic device10 a in accordance with another embodiment of the invention. In thisembodiment, the microelectronic device la includes a substrate 20, a die40 attached to the substrate 20 by an adhesive 60, and the first andsecond covers 70 a and 70 b. The microelectronic device 10 a can alsoinclude a plurality of pressure relief elements 80 that are defined bypassageways 82 extending through the substrate 20. Unlike themicroelectronic device 10 in which the passageways 82 extend to theadhesive 60, the pressure relief elements 80 of the microelectronicdevice 10 are defined by passageways 82 that extend from the firstsurface 23 of the substrate 20 to the second surface 24 of the substrate20 at a location over the first cover 70 a and spaced apart from theadhesive 60. The microelectronic device 10 a accordingly providespressure relief elements 80 for allowing moisture to diffuse out of thesubstrate 20 and the first cover 70 a during high temperatureprocessing. In another embodiment, the pressure relief elements 80 shownin FIGS. 2B and 3 are combined in a single microelectronic device havinga first plurality of pressure relief elements 80 that expose theadhesive 60 to the external environment (FIG. 2A) and a second pluralityof pressure relief elements 80 expose the interior of the first cover 70a to an external environment (FIG. 3).

[0028]FIG. 4A is a bottom isometric view and FIG. 4B is a frontcross-sectional view of a microelectronic device 10 c in accordance withanother embodiment of the invention. Referring to FIG. 4A, themicroelectronic device 10 c has a plurality of pressure relief elements80 extending through the first cover 70 a. Referring to FIG. 4B, thepressure relief elements 80 can be a series of passageways 82 extendingthrough a top portion of the first cover 70 a. Each passageway 82 canhave an opening 84 exposed to external environment and an interior point86 at the backside 45 of the die 40. In operation, the pressure reliefelements 80 shown in FIG. 4B allow moisture to escape from the firstcover 70 a during high temperature processing.

[0029]FIGS. 5A and 5B are front cross-sectional views of amicroelectronic device 500 in accordance with another embodiment of theinvention. Referring to FIG. 5A, the microelectronic device 500 includesa substrate 520 having a first surface 523 and a second surface 524. Thedie 40 is attached to the second surface 524 of the substrate 520, thefirst cover 70 a encases the die 40, and the second cover 70 b encasesthe bond-pads 42 and the wire-bond lines 50 at the first surface 523 ofthe substrate 520. Several components of the microelectronic device 500can be similar to the components of the microelectronic device 10 shownin FIG. 2B, and thus like reference numbers refer to like components inFIGS. 2B, 5A and 5B. The substrate 520, for example, can also have aslot 25, a plurality of contact elements 28 adjacent to the slot 25, aplurality of ball-pads 27 spaced apart from the contact elements 28, anda plurality of conductive elements electrically coupling selectedcontact elements to corresponding ball-pads 27.

[0030] The microelectronic device 500 can also include a plurality ofpressure relief elements 580 through a portion of the substrate 520. Inthe embodiment illustrated in FIG. 5A, the pressure relief elements 580are depressions 582 that have an opening 584 at the first surface 523 onthe substrate 520 and an interior point 586 proximate to the secondsurface 524 of the substrate 520. The depressions 582 do not extendcompletely through the substrate 520 such that the interior point 586 ofthe pressure relief elements 580 is at an intermediate depth in thesubstrate 520. The pressure relief elements 580 can be superimposed overthe adhesive strips 60 (shown in FIG. 5A), or the pressure relief 580can be located over the first cover 70 a in a manner similar to thepressure relief elements 80 shown in FIG. 3.

[0031]FIG. 5B illustrates the operation of the pressure relief elements580 in the microelectronic device 500. As the microelectronic device 500is heated during a high temperature process, the expanding moisture inthe adhesive 60, the substrate 520, and/or the covers 70 a and 70 b canrupture the thin section of the substrate 520 at the interior point 586of a passageway 582 to form a via 588 through which the expanding gascan escape. The pressure relief elements 580 accordingly act as pressurerelief valves that rupture to prevent the pressure gradient frombecoming so large that it cracks or otherwise delaminates the first orsecond covers 70 a or 70 b. The thickness “t” of the thin section of thesubstrate 520 between the interior point 586 and the second surface 524can accordingly be selected to rupture and form the via 588 at apressure that is less than the failure pressure of the first and secondcovers 70 a and 70 b.

[0032] The pressure relief elements 580 can also be fabricated by lasercutting, etching, drilling, stamping, embossing, or molding thesubstrate 520. A laser, for example, can have a residence time that doesnot penetrate through the substrate 520 but rather only forms thedepression 582 without passing through the second surface 524. Suitablelaser and etching techniques that can form a controlled depression areknown in the art.

[0033]FIGS. 6A and 6B are front cross-sectional views of amicroelectronic device 600 in accordance with yet another embodiment ofthe invention. Several components of the microelectronic device 600 canbe similar to the components of the microelectronic device 10 shown inFIG. 2B, and thus like reference numbers refer to like parts in FIGS.2B, 6A and 6B. The microelectronic device 600 can also include aplurality of pressure relief elements 680 through a portion of the firstcover 70 a. The pressure relief elements 680, for example, can be aplurality of depressions 682 having an opening 684 and an interior point686. The opening 684 is exposed to external environment, and theinterior point 686 is at an intermediate depth in the first cover 70 a.Referring to FIG. 6B, the thin section of the first cover 70 a betweenthe interior point 686 and the backside 45 of the die 40 can ruptureduring a high temperature process to relieve pressure in the first cover70 a. The left-most pressure relief element 680 a in FIG. 6B, forexample, illustrates a ruptured pressure relief element 680 that forms avia 688 through which high pressure gas can escape from themicroelectronic device 600. As set forth above, the thickness t of thefirst cover 70 a between the back side 45 of the die 40 and the interiorpoint 686 of the pressure relief element 680 can be selected to ruptureat a predetermined pressure that is less than the failure pressure ofthe thicker portion of the cover 70 a. As such, the pressure reliefelements 680 can act as pressure relief valves that are positioned atpredetermined failure sites to relieve pressure within themicroelectronic device 600 before the first cover 70 a or the secondcover 70 b cracks or has another type of catastrophic failure.

[0034]FIG. 7 is a side cross-sectional view of a mold assembly and amethod for forming the first cover 70 a for the microelectronic device600 shown in FIGS. 6A and 6B. The mold assembly can include a first moldsection 200 and a second mold section 300. The first mold section 200has a bearing surface 220 and a wire-side cavity 224, and the secondmold section 300 has a bearing surface 320, a die-side cavity 324, and aplurality of posts 329 in the die-side cavity 324. The wire-side cavity224 is configured to form the second cover 70 b over the slot 25 of thesubstrate 20, and the die-side cavity 324 is configured to form thefirst cover 70 a over the die 40. The second mold section 300 can alsoinclude a gate 326 and an injection chamber 328 through which a flow Fof mold compound (e.g., thermosetting material) is injected into thedie-side cavity 324.

[0035] During the molding process, the substrate 20 is positionedbetween the first and second mold sections 200 and 300 to align the die40 with the die-side cavity 324 and to align the slot 25 with thewire-side cavity 224. The bearing surface 320 of the second mold section300 presses against the second surface 24 of the substrate 20, and thebearing surface 220 of the first mold section 200 can press against thefirst surface 23 of the substrate 20. The bearing surface 220 of thefirst mold section 200 can engage the first surface 23 of the substrate20 by injecting a mold compound into the die-side cavity 324, asexplained in U.S. patent application No. 09/255,554. The flow of moldcompound F initially passes through gate 326 of the second mold section300 and continues into the die-side cavity 324 to create a first flow A₁of mold compound heading in a first direction toward the second end 22of the substrate 20. The first flow A₁ of mold compound passes throughthe aperture 26 in the substrate 20 to generate a second flow B₁ of moldcompound that flows through the wire-side cavity 224 of the first moldsection 200. The second flow B₁ of mold compound fills the slot 25 ofthe substrate 20 and flows in a second direction until it reaches aterminal end 227 of the wire-side cavity 224. When the mold compoundsufficiently fills the die-side cavity 324 and the wire-side cavity 224,the post 329 in the die-side cavity 324 form the pressure reliefelements 680 in the first cover 70 a shown in FIGS. 6A and 6B.Similarly, to form the pressure relief elements 80 in the first cover 70a shown in FIG. 4B, the posts 329 can be lengthened so that they engagethe back side 45 of the substrate 40 when the bearing surface 320 of thesecond mold section 300 engages the second surface 24 of the substrate20.

[0036] From the foregoing it will be appreciated that specificembodiments of the invention have been disclosed for purposes ofenablement and illustration, but that various modifications may be madewithout deviating from the spirit and scope of the invention. Forexample, certain embodiments of the pressure relief elements 80 shown inFIGS. 2A-3 or the pressure relief elements 580 shown in FIGS. 5A and 5Bcan also relieve pressures caused by mechanical stresses as a result ofthe different coefficients of thermal expansion for the differentcomponents of the microelectronic device 10. The substrate 20 generallyhas a different coefficient of thermal expansion than the moldingcompound of the first and second covers 70 a and 70 b. Themicroelectronic device 10 generally has a low level of internalmechanical stress at room temperature because the first and secondcovers 70 a and 70 b shrink after cooling from the molding process.During high temperature processing, however, the microelectronicsubstrate 10 can have high internal mechanical stresses because thefirst and second covers 70 a and 70 b can expand much more than thesubstrate 20. The elongated pressure relief elements 80 shown on the oneside of the cover 70 b in FIG. 2A are expected to reduce the internalmechanical stresses caused by different thermal expansion/contractioncharacteristics of the different components in the microelectronicdevice 10 because the elongated pressure relief elements 80 act asexpansion joints. Thus, the term pressure relief element can includestructures that provide a path through which gas can escape from themicroelectronic device, that relieve internal mechanical stresses causedby different thermal expansion/contraction characteristics, and/or thatcontrol or otherwise dissipate other internal stresses inmicroelectronic devices. Accordingly, the invention is not limitedexcept by the appended claims.

1. A packaged microelectronic device, comprising: a microelectronic diehaving an integrated circuit and a bond-pad array having a plurality ofbond-pads operatively coupled to the integrated circuit; aninterconnecting unit having a substrate with a first side and a secondside to which the die is attached, a plurality of contact elementsoperatively coupled to corresponding bond-pads on the die, a pluralityof ball-pads on the first side, and a plurality of conductive elementsextending from selected contact elements to corresponding ball-pads; aprotective casing having at least a first cover encapsulating the die onthe second side of the substrate; and a pressure relief element throughat least a portion of the first cover and/or the substrate, the pressurerelief element having an opening to an external environment and apassageway to an internal location.
 2. The device of claim 1 wherein thepressure relief element is a hole completely through the substrate suchthat the opening is at the first side of the substrate and the internallocation is at the second side of the substrate.
 3. The device of claim2 wherein: the microelectronic die is attached to the second side of thesubstrate by an adhesive; and the pressure relief element is over theadhesive such that the adhesive is exposed to the external environmentthrough the passageway.
 4. The device of claim 1 wherein the pressurerelief element is an elongated channel completely through the substratesuch that the opening is at the first side of the substrate and theinternal location is at the second side of the substrate.
 5. The deviceof claim 4 wherein: the microelectronic die is attached to the secondside of the substrate by an adhesive; and the pressure relief element isover the adhesive such that the adhesive is exposed to the externalenvironment through the passageway.
 6. The device of claim 1 wherein thepressure relief element is a depression in the substrate that does notpass completely through the substrate such that the opening is at thefirst side of the substrate and the internal location is at anintermediate depth within the substrate, the substrate having athickness between the internal location and the second side that isconfigured to rupture at a predetermined pressure.
 7. The device ofclaim 6 wherein: the microelectronic die is attached to the second sideof the substrate by an adhesive; and the depression is over theadhesive.
 8. The device of claim 1 wherein the pressure relief elementis a hole completely through the first cover such that the internallocation is at a backside of the die.
 9. The device of claim 1 whereinthe pressure relief element is a depression in the first cover that doesnot pass completely through the first cover such that the internallocation is at an intermediate depth within the first cover, the firstcover having a thickness between the internal location and a backside ofthe die that is configured to rupture at a predetermined pressure.
 10. Apackaged microelectronic device, comprising: a microelectronic diehaving an integrated circuit and a bond-pad array having a plurality ofbond-pads operatively coupled to the integrated circuit; aninterconnecting unit having a substrate with a first side and a secondside to which the die is attached, a plurality of contact elementsoperatively coupled to corresponding bond-pads on the die, a pluralityof ball-pads on the first side, and a plurality of conductive elementsextending from selected contact elements to corresponding ball-pads; aprotective casing having at least a first cover encapsulating the die onthe second side of the substrate; and a pressure relief element throughat least a portion of the first cover and/or the substrate, the pressurerelief element being configured to release a gas entrapped by the casingand/or the substrate.
 11. The device of claim 10 wherein the pressurerelief element is a hole completely through the substrate such that theopening is at the first side of the substrate and the internal locationis at the second side of the substrate.
 12. The device of claim 11wherein: the microelectronic die is attached to the second side of thesubstrate by an adhesive; and the pressure relief element is over theadhesive such that the adhesive is exposed to the external environmentthrough the passageway.
 13. The device of claim 10 wherein the pressurerelief element is an elongated channel completely through the substratesuch that the opening is at the first side of the substrate and theinternal location is at the second side of the substrate.
 14. The deviceof claim 13 wherein: the microelectronic die is attached to the secondside of the substrate by an adhesive; and the pressure relief element isover the adhesive such that the adhesive is exposed to the externalenvironment through the passageway.
 15. The device of claim 10 whereinthe pressure relief element is a depression in the substrate that doesnot pass completely through the substrate such that the opening is atthe first side of the substrate and the internal location is at anintermediate depth within the substrate, the substrate having athickness between the internal location and the second side that isconfigured to rupture at a predetermined pressure.
 16. The device ofclaim 15 wherein: the microelectronic die is attached to the second sideof the substrate by an adhesive; and the depression is over theadhesive.
 17. The device of claim 10 wherein the pressure relief elementis a hole completely through the first cover such that the internallocation is at a backside of the die.
 18. The device of claim 10 whereinthe pressure relief element is a depression in the first cover that doesnot pass completely through the first cover such that the internallocation is at an intermediate depth within the first cover, the firstcover having a thickness between the internal location and a backside ofthe die that is configured to rupture at a predetermined pressure.
 19. Apackaged microelectronic device, comprising: an interconnecting unithaving a substrate with a first side and a second side, a slot definingan open region between the first and second sides, a plurality ofcontact elements on the first side and adjacent to the slot, a pluralityof ball-pads on the first side, and a plurality of conductive elementson the first side extending from selected contact elements tocorresponding ball-pads; a microelectronic die having an integratedcircuit and a plurality of bond-pads operatively coupled to theintegrated circuit, the die being attached to the second side of thesubstrates, and the bond-pads being aligned with the slot; a pluralityof wire-bond lines in the slot extending between selected bond-pads onthe die and corresponding contact elements on the substrate; aprotective casing having a first cover encapsulating the die on thesecond side of the substrate and a second cover encapsulating thebond-pads, the wire-bond lines and the contact elements; and a firstpressure relief element through at least a portion of the first coverand/or the substrate, the pressure relief element being configured torelease a gas entrapped by the casing and/or the substrate.
 20. Thedevice of claim 19 wherein the pressure relief element is a holecompletely through the substrate such that the opening is at the firstside of the substrate and the internal location is at the second side ofthe substrate.
 21. The device of claim 20 wherein: the microelectronicdie is attached to the second side of the substrate by an adhesive; andthe pressure relief element is over the adhesive such that the adhesiveis exposed to the external environment through the passageway.
 22. Thedevice of claim 19 wherein the pressure relief element is an elongatedchannel completely through the substrate such that the opening is at thefirst side of the substrate and the internal location is at the secondside of the substrate.
 23. The device of claim 22 wherein: themicroelectronic die is attached to the second side of the substrate byan adhesive; and the pressure relief element is over the adhesive suchthat the adhesive is exposed to the external environment through thepassageway.
 24. The device of claim 19 wherein the pressure reliefelement is a depression in the substrate that does not pass completelythrough the substrate such that the opening is at the first side of thesubstrate and the internal location is at an intermediate depth withinthe substrate, the substrate having a thickness between the internallocation and the second side that is configured to rupture at apredetermined pressure.
 25. The device of claim 24 wherein: themicroelectronic die is attached to the second side of the substrate byan adhesive; and the depression is over the adhesive.
 26. The device ofclaim 19 wherein the pressure relief element is a hole completelythrough the first cover such that the internal location is at a backsideof the die.
 27. The device of claim 19 wherein the pressure reliefelement is a depression in the first cover that does not pass completelythrough the first cover such that the internal location is at anintermediate depth within the first cover, the first cover having athickness between the internal location and a backside of the die thatis configured to rupture at a predetermined pressure.
 28. Aninterconnecting unit for use in packaging a microelectronic device,comprising: a substrate with a first side and a second side, the secondside being configured to receive the die; a contact array with aplurality of contact elements on the first side and/or the second side;a ball-pad array with a plurality of ball-pads on the first side; aplurality of conductive elements extending from selected contactelements to corresponding ball-pads; and a pressure relief elementthrough at least a portion of the substrate positioned at a locationapart from the contact elements, the pressure relief element having anopening at the first side of the substrate and an internal location atleast proximate to the second side of the substrate.
 29. The unit ofclaim 28 wherein the pressure relief element is a hole completelythrough the substrate such that the opening is at the first side of thesubstrate and the internal location is at the second side of thesubstrate.
 30. The unit of claim 29 wherein: the interconnecting unitfurther comprises an adhesive attached to the second side of thesubstrate; and the pressure relief element is over the adhesive suchthat the adhesive is exposed to the external environment through thepassageway.
 31. The unit of claim 28 wherein the pressure relief elementis an elongated channel completely through the substrate such that theopening is at the first side of the substrate and the internal locationis at the second side of the substrate.
 32. The unit of claim 31wherein: the interconnecting unit further comprises an adhesive attachedto the second side of the substrate; and the pressure relief element isover the adhesive such that the adhesive is exposed to the externalenvironment through the passageway.
 33. The unit of claim 28 wherein thepressure relief element is a depression in the substrate that does notpass completely through the substrate such that the opening is at thefirst side of the substrate and the internal location is at anintermediate depth within the substrate, the substrate having athickness between the internal location and the second side configuredto rupture at a predetermined pressure.
 34. The unit of claim 33wherein: the interconnecting unit further comprises an adhesive attachedto the second side of the substrate; and the depression is over theadhesive.
 35. A method for manufacturing a packaged microelectronicdevice having a die with an integrated circuit and a plurality ofbond-pads operatively coupled to the integrated circuit, comprising:providing an interconnecting unit having a substrate with a first sideand a second side, a plurality of contact elements on the first sideand/or the second side, a plurality of ball-pads on the first side, anda plurality of conductive elements extending from selected contactelements to corresponding ball-pads; attaching a microelectronic die tothe second side of the substrate, the die having an integrated circuitand a plurality of bond-pads coupled to the integrated circuit;encapsulating the die with a first cover; and providing pressure reliefelements in the first cover and/or the substrate that are configured torelease a gas entrapped by the first cover and/or the substrate.
 36. Themethod of claim 35 wherein providing pressure relief elements comprisesforming a plurality of passageways in the substrate, the passagewayshaving an opening at the first surface of the substrate and an interiorpoint defining another opening at the second surface of the substrate.37. The method of claim 36 wherein forming the passageways comprisesfabricating holes in the substrate to be superimposed over an adhesiveattaching the die to the second side of the substrate.
 38. The method ofclaim 36 wherein forming the passageways comprises fabricating slot inthe substrate to be superimposed over an adhesive attaching the die tothe second side of the substrate.
 39. The method of claim 35 whereinproviding pressure relief elements comprises forming a plurality ofdepressions in the substrate, the depressions having an opening at thefirst surface of the substrate and an interior point at an intermediatedepth in the substrate.
 40. The method of claim 39 wherein forming thedepressions comprises positioning the depressions to be superimposedover an adhesive attaching the die to the second side of the substrate.41. The method of claim 39 wherein forming the depressions comprisespositioning the depressions to be superimposed over a portion of thefirst cover.
 42. The method of claim 35 wherein providing pressurerelief elements comprises forming a plurality of passageways in thefirst cover, the passageways having an opening exposed to an externalenvironment and an interior point at a backside of the die.
 43. Themethod of claim 42 wherein providing pressure relief elements comprisesforming a plurality of depressions in the first cover, the depressionshaving an opening exposed to an external environment and an interiorpoint at an intermediate depth within the first cover over a backside ofthe die.
 44. The method of claim 35 wherein providing pressure reliefelements comprises forming a plurality of passageways in the firstcover, the passageways having an opening exposed to an externalenvironment and an interior point defining another opening at the secondside of the substrate.
 45. A method for processing a packagedmicroelectronic device having a die with an integrated circuit and aplurality of bond-pads operatively coupled to the integrated circuit,comprising: providing a packaged microelectronic device including amicroelectronic die, an interconnecting unit, and a casing, wherein thedie comprises an integrated circuit and a plurality of bond-pads coupledto the integrated circuit, wherein the interconnecting unit comprises asubstrate with a first side and a second side to which the die isattached, a plurality of contact elements operatively coupled to thebond-pads on the die, a plurality of ball-pads on the first side, and aplurality of conductive elements extending from selected contactelements to corresponding ball-pads, and wherein the casing comprises atleast a first cover encapsulating the die; heating the packaged device;and releasing a gas entrapped by the first cover and/or the substratethrough a pressure relief element.
 46. The method of claim 45 whereinreleasing a gas comprises passing moisture through a plurality of holesin the substrate that are positioned over an adhesive attaching the dieto the second side of the substrate and/or the first cover.
 47. Themethod of claim 45 wherein releasing a gas comprise passing moisturethrough a via formed by rupturing a thin section of the substratebetween the second surface of the substrate and a depression in thefirst surface of the substrate.
 48. The method of claim 45 whereinreleasing a gas comprises passing moisture through a plurality of holesin the first cover that are positioned over a backside of the die and/orthe second side of the substrate.
 49. The method of claim 45 whereinreleasing a gas comprises passing moisture through a via formed byrupturing a thin section of the substrate under a depression in thefirst cover.